Ultrasonography is known as one of imaging examination methods that allow non-invasive examination of the state of the interior of a living body. In ultrasonography, an ultrasound probe that can transmit and receive ultrasound is used. Ultrasound transmitted from the ultrasound probe to the subject (living body) travels through the interior of the living body and is reflected at a tissue interface. Then, the reflected ultrasound is received by the ultrasound probe. Based on the time taken for the reflected ultrasound to return to the ultrasound probe, the distance is calculated, thereby imaging the state of the interior.
Further, photoacoustic imaging, which images the interior of a living body using the photoacoustic effect, is known. In photoacoustic imaging, in general, pulsed laser light, for example, is applied to the interior of a living body. In the interior of the living body, a living tissue absorbs energy of the pulsed laser light and ultrasound (a photoacoustic signal) is generated due to adiabatic expansion caused by the energy. This photoacoustic signal is detected using an ultrasound probe, or the like, and a photoacoustic image is constructed based on the detected signal, thereby visualizing the interior of the living body based on the photoacoustic signal.
Usually, in a ultrasound probe, the interior of the probe body is filled with a potting agent to secure parts contained in the probe body. Potting the interior of the probe body is taught, for example, in Japanese Unexamined Patent Publication Nos. 7(1995)-313507 and 8(1996)-010255 (hereinafter, Patent Documents 1 and 2). As the potting agent, an epoxy resin, etc., may be used, for example.
In the photoacoustic imaging, light from a laser light source may be guided to the ultrasound probe using an optical fiber, or the like, to apply the laser light from the ultrasound probe. An ultrasound probe including a light application section is taught in Japanese Unexamined Patent Publication No. 2008-49063 (hereinafter, Patent Document 3), for example. Patent Document 3 teaches that the end portion of the optical fiber on the light exit end side is disposed adjacent to ultrasound transducers and secured integrally with the ultrasound transducers. The light exit end of the optical fiber is secured in a hole provided in a holder such that the light is applied in a direction in which ultrasound from the ultrasound transducers travels.